1. Field of the Invention
This invention relates to an access door primarily designed to provide an insulated entrance to heating, ventilating and air conditioning ducts. More particularly, this invention pertains to a two-pan structure lockably connected together and hinged to the duct. By a simple unfastening action, access to the duct is provided.
2. Description of the Prior Art
Presently there exist numerous devices, generally doors, designed to provide an entrance to an area. When doors are utilized, they generally are the conventional fixed hinged door although more elaborate swinging or removable arrangements may be used. Doors of this type provide access to areas such as electrical panel boxes, wall service outlets and plumbing networks. Typical access door assemblies are seen in U.S. Pat. Nos. 3,537,212, 2,766,856 and 1,921,051. For certain needs, such as air conditioning ducts, removable panels have been devised. They usually comprise a frame securely fastened to the surrounding wall of the duct. A flat sheet metal pan easily disconnectable from the frame enables easy access. Since the frame must be securely fastened to the wall, its installation is quite expensive. For sheet metal work, expensive installation is undesirable.
The prior art also discloses closures designed to removably seal apertures such as windows. For example, U.S. Pat. No. 2,772,447 discloses a panel assembly connected to the wall by a fastening means. The fastening means comprises a plurality of beams straddling the aperture on the opposite side of the said wall. Such closure means do not comprise an easy access door. They require complete removal of the closure means and for such reason, are too cumbersome. Also such closure means do not easily provide acoustical or thermal insulation properties nor are they generally aesthetically pleasing.
Since mechanisms such as fire dampers contained within ducts periodically require inspection and servicing, it is most desirous for the access to insulatingly cover the opening and then, when need be, allow convenient access to the mechanism.
An object of this invention is to provide a simple, yet durable structured access door.
Another object is to provide an insulated access door.
Still another object is to provide an access door which facilitates easy entrance into the aperture.
Another object is to provide an access door which has unique hinge and fastening means facilitating quick and easy entrance.
Another object is to provide an access door which can be quickly and easily installed in ducts.
Other objects of the invention will in part be obvious and will in part appear hereinafter.